The processing or casting of copper articles may require a bath containing molten copper, and this bath of molten copper may be maintained at temperatures of around 1100° C. Many instruments or devices may be used to monitor or to test the conditions of the molten copper in the bath, as well as for the final production or casting of the desired copper article. There is a need for these instruments or devices to better withstand the elevated temperatures encountered in the molten copper bath, beneficially having a longer lifetime and limited to no reactivity with molten copper.